{"id":38754,"date":"2019-07-29T08:39:18","date_gmt":"2019-07-29T12:39:18","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=38754"},"modified":"2019-07-29T08:39:18","modified_gmt":"2019-07-29T12:39:18","slug":"imres-hanrongda-hrd-737-modification-increases-sensitivity","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2019\/07\/imres-hanrongda-hrd-737-modification-increases-sensitivity\/","title":{"rendered":"Imre’s HanRongDa HRD-737 modification increases sensitivity"},"content":{"rendered":"

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Many thanks to SWLing Post<\/em> contributor, Imre Olajos, who writes:<\/p>\n

Hi, HRD 737 lovers! I have a good news!<\/p>\n

I\u00a0 (became brave enough to) modify my HRD-737<\/a>.<\/p>\n

I tried reverse-engineering- but I gave up. No numbers on IC-s. I found specifications for the analog switches (one for each band ) and found information about the transistors around those analog switch IC-s. Nice, 1 GHz fT transistors, all surface mount, so I gave up that line.<\/p>\n

I found an NPN SM transistor in a damaged TV remote. It is only a 300 MHz transistor but
\nI had no better than that, so I started to build a little antenna amplifier circuit, wide band and simple.<\/p>\n

I lost a few SM capacitors during the soldering but I have plenty of those. So the 1\/4 square inch circuit board was finished last week. I tested it with an external 3 volt battery and I found it good working. Today ( 07-27-2019 ) I opened up the HRD-737 and wired it into the radio.
\nThe results are much better than I expected. The HDR-737 became a good shortwave radio!<\/p>\n

When I touch the built in antenna by my finger, radio is sensing the touch and station comes in. This effect was not there before. Radio became more sensitive on CB band than my Realistic DX392.<\/p>\n

I have a YouTube channel<\/a> [in the following video\/slideshow] and I will show you the little ugly but great working circuit in the radio:<\/p><\/blockquote>\n